core: Add node-style memory reservation to device tree

Linux supports a newer memory reservation layout in the device-tree,
where each reservation is represented by a subnode under a top-level
"reserved-memory" node.

This change adds these nodes, using the mem_region names as the property
names (minus any cell addresses). The reserved-memory node looks like
this:

/ {
	name = "reserved-memory";
	ranges;
	#address-cells = <0x2>;
	#size-cells = <0x2>;

	ibm,firmware-code@30000000 {
		reg = <0x0 0x30000000 0x0 0x200000>;
	};

	ibm,firmware-data@30e00000 {
		reg = <0x0 0x30e00000 0x0 0xc00000>;
	};

	ibm,firmware-stacks@31a00000 {
		reg = <0x0 0x31a00000 0x0 0x8000000>;
	};

	ibm,firmware-allocs-memory@39a00000 {
		reg = <0x0 0x39a00000 0x0 0x1c0200>;
	};

	ibm,firmware-heap@30200000 {
		reg = <0x0 0x30200000 0x0 0xc00000>;
	};
};

We also store a pointer to the reservation nodes in struct mem_region,
so they can be used by other skiboot code.

We keep the property-style reservation information (reserved-names and
reserved-ranges) unchanged.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/doc/device-tree/reserved-memory.txt b/doc/device-tree/reserved-memory.txt
new file mode 100644
index 0000000..0f6002d
--- /dev/null
+++ b/doc/device-tree/reserved-memory.txt
@@ -0,0 +1,27 @@
+reserved-memory device tree nodes
+
+OPAL exposes reserved memory through a top-level reserved-memory node,
+containing subnodes that represent each reserved memory region.
+
+This follows the Linux specification for the /reserved-memory node,
+described in the kernel source tree, in:
+
+  Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+
+The top-level /reserved-memory node contains:
+
+  #size-cells = <2>
+  #address-cells = <2>
+   - addresses and sizes are all 64-bits
+
+  ranges;
+   - the empty ranges node indicates no translation of physical
+     addresses in the subnodes.
+
+The sub-nodes under the /reserved-memory node contain:
+
+ reg = <address size>
+  - the address and size of the reserved memory region. The address
+    and size values are two cells each, as signified by the top-level
+    #{address,size}-cells
+